XX-net/XX-Net · warning

DNS server:%s domain:%s fail t:%f

Error message

DNS server:%s domain:%s fail t:%f

What it means

query_json() in the DoH client sends a GET request to the resolver's JSON API (RFC 8484 JSON style, e.g. Cloudflare/Google) and the HTTP client returned a falsy/None response. The request failed before any HTTP data was processed (connection error, blocked request, or the client's internal failure), so an empty IP list is returned.

Source

Thrown at code/default/smart_router/local/dns_query.py:542

            }, timeout=self.timeout)
        else:
            return simple_http_client.Client(timeout=self.timeout)

    @property
    def server(self):
        return random.choice(self.other_servers)

    def query_json(self, domain, dns_type=1):
        try:
            t0 = time.time()
            client = self.get_connection()

            url = self.server + "?name=" + domain + "&type=A" # type need to map to Text.
            r = client.request("GET", url, headers={"accept": "application/dns-json"})
            t2 = time.time()
            ips = []
            if not r:
                xlog.warn("DNS server:%s domain:%s fail t:%f", self.server, domain,  t2 - t0)
                return ips

            t = utils.to_str(r.text)

            data = json.loads(t)
            for answer in data["Answer"]:
                ips.append(answer["data"])

            self.connections.append([client, time.time()])

            xlog.debug("DNS server:%s query:%s return %s t:%f", self.server, domain, ips, t2 - t0)
            return ips
        except Exception as e:
            xlog.warn("DNSOverHttpsQuery query fail:%r", e)
            return []

    def query(self, domain, dns_type=1, url=None):
        t0 = time.time()

View on GitHub (pinned to cfa5bc17b6)

Solutions

  1. Verify the DoH endpoint manually: 'curl -H 'accept: application/dns-json' 'https://1.1.1.1/dns-query?name=example.com&type=A''
  2. Ensure self.server points at a JSON-capable DoH resolver (Cloudflare, Google) and not a pure RFC8484 wire-format endpoint
  3. Check proxy/TLS settings of the HTTP client used by this module
  4. Retry with backoff — transient HTTPS failures are common; consider a second DoH provider as fallback
Defensive patterns

Strategy: retry

Validate before calling

import requests
def doh_endpoint_ok(server):
    try:
        r = requests.get(server, params={'name': 'example.com', 'type': 'A'},
                         headers={'accept': 'application/dns-json'}, timeout=5)
        return r.status_code == 200 and 'Answer' in r.json()
    except Exception:
        return False

Try / catch

for server in doh_servers:  # rotate providers
    ips = doh_client.query(domain)
    if ips:
        break

Prevention

When it happens

Trigger: Calling query() on DnsOverHttpsQuery when the HTTPS request to self.server fails to connect or is rejected — DNS URL wrong, proxy required but unavailable, TLS failure, or the endpoint blocked/returning nothing the client accepts.

Common situations: DoH endpoint blocked or hijacked on the network, wrong self.server URL (must support ?name=&type=A JSON API), corporate TLS-inspection proxies breaking the request, no internet connectivity, GFW-style blocking of well-known DoH providers.

Related errors

AI-assisted analysis of XX-net/XX-Net@cfa5bc17b6 (2026-08-27). Data as JSON: /api/errors/4f22233ab69a27cf. Report an issue: GitHub.